能量代谢分子SIRT1在运动改善2型糖尿病骨代谢中的作用机制

文题释义： 沉默信息调节因子1(silent information regulator 1，SIRT1)：是调控能量代谢的关键因子，其通过细胞氧化还原等途径来介导能量代谢、基因转录、细胞衰老等生理学过程。研究发现，SIRT1在调控成骨细胞和破骨细胞分化、增殖和活性上均扮演重要角色。 骨代谢：骨的功能是为肌肉收缩提供附着处及保护内脏等重要的生命器官。一般认为骨在细胞水平上是不活跃的，事实上骨的细胞在不停地进行着细胞代谢，不仅骨的细胞之间会相互作用，还存在骨髓中的红细胞生成细胞、基质细胞相互作用，以进行骨的改建和重建。 背景：能量代谢调控2型糖尿病骨代谢是近来生命医学领域的研究热点。长期糖、脂等能量代谢的紊乱导致胰岛素抵抗，引发2型糖尿病。而沉默信息调节因子1(SIRT1)作为一种烟酰胺腺嘌呤二核苷酸(NAD+)依赖的组蛋白去乙酰化酶，是调控能量代谢关键因子，还参与骨代谢、基因转录、细胞衰老、凋亡及焦亡等。 目的：分析近年来有关SIRT1在运动改善骨代谢中的作用机制的相关文献，研究其现状和研究进展。 方法：在PubMed、CNKI等数据库进行检索，中文关键词：SIRT1，运动，2型糖尿病，骨形成，骨吸收；英文关键词：SIRT1, exercise, type 2 diabetes, bone formation, bone resorption。 结果与结论：①成骨细胞和破骨细胞的分化和功能发挥以及相互之间的代谢平衡是保障骨代谢稳态的关键。而一旦发生紊乱将会导致骨组织形态结构退化，这也是2型糖尿病并发症骨质疏松发生的重要机制；②能量代谢紊乱是引发2型糖尿病的关键，那么SIRT1作为调控能量代谢关键因子，其可通过Wnt、转化生长因子β等途径介导成骨细胞和破骨细胞分化及功能；③近来，研究发现运动可显著改善2型糖尿病的能量代谢和骨代谢，文章从成骨细胞、破骨细胞出发，通过综述目前国内外相关研究，探究SIRT1在运动改善2型糖尿病骨代谢中的作用机制。 ORCID: 0000-0002-3135-9409(张路遥) 中国组织工程研究杂志出版内容重点：组织构建；骨细胞；软骨细胞；细胞培养；成纤维细胞；血管内皮细胞；骨质疏松；组织工程     

糖尿病相关骨转换指标研究进展

骨质疏松症是糖尿病常见并发症之一,也是影响糖尿病患者生存质量及寿命的主要原因.骨密度(bone mineral density,BMD)测定是早期诊断骨质疏松的标准,然而,一些BMD正常的潜在骨质疏松患者易被忽略.因此,寻找敏感性和特异性更高的骨代谢标志物来预测早期骨代谢异常具有重要意义.     

2型糖尿病男性患者骨代谢指标与骨密度的相关性研究

目的：探讨2型糖尿病男性患者骨密度与骨代谢生化指标间的关系。方法：选取我科2014年1月至2015年12月入院的2型糖尿病男性患者102例,采用双能X线骨密度仪,测定腰椎(L2~L4)、股骨上端[包括股骨颈(Neck)、华氏三角(Ward)及股骨粗隆(Troch)]和全身的骨密度(bone mineral density, BMD)值;根据T值将这些患者分为骨量正常组(44例)、骨量减少组(36例)和骨质疏松组(29例),采用酶联免疫法测定各组碱性磷酸酶(alkaline phosphatase,ALP)、N-端中段骨钙素(N-MID-OT)、总Ⅰ型胶原氨基端延长肽(type 1 amino-terminal propeptide,tP1NP)和β胶原特殊序列(β-CTX)的浓度,比较三组骨代谢指标的变化,并对BMD与各项骨代谢指标进行相关性分析。结果：随着骨密度的降低,骨代谢指标的水平逐渐增高,其中,N-MID-OT和β-CTX的水平在三组间的差异皆有统计学意义(P<0.05);tP1NP在骨质疏松组和其余两组有统计学差异(P<0.05);ALP在三组间无统计学差异(P>0.05)。骨量减少组中,N-MID-OT与Neck、Troch及全身的BMD呈负相关(r=?0.754,?0.663,?0.743;P<0.05),β-CTX与Ward的BMD呈负相关(r=?0.273;P<0.05);骨质疏松组中, N-MID-OT与所有部位的BMD呈负相关(r=?0.736,?0.562,?0.715,?0.521,?0.436;P<0.05),β-CTX与Neck、Ward及全身的BMD呈负相关(r=?0.532,?0.614,?0.764;P<0.05)。结论：2型糖尿病男性患者骨密度与骨代谢指标呈负相关,两者联合评估有助于早期预防骨质疏松。     

Long-term reaction to bone cement in osteoporotic bone: new bone formation in vertebral bodies after vertebroplasty

Elderly patients frequently suffer from osteoporotic vertebral fractures resulting in the need of vertebroplasty or kyphoplasty. Nevertheless, no data are available about the long-term consequences of cement injection into osteoporotic bone. Therefore, the aim of the present study was to evaluate the long-term tissue reaction on bone cement injected to osteoporotic bone during vertebroplasty. The thoracic spine of an 80-year-old female was explanted 3.5 years after vertebroplasty with polymethylmethacrylate. The treatment had been performed due to painful osteoporotic compression fractures. Individual vertebral bodies were cut in axial or sagittal sections after embedding. The sections were analysed using contact radiography and staining with toluidine blue. Furthermore, selected samples were evaluated with scanning electron microscopy and micro-compted tomography (in-plane resolution 6 microm). Large amounts of newly formed callus surrounding the injected polymethylmethacrylate were detected with all imaging techniques. The callus formation almost completely filled the spaces between the vertebral endplate, the cancellous bone, and the injected polymethylmethacrylate. In trabecular bone microfractures and osteoclast lacuna were bridged or filled with newly formed bone. Nevertheless, the majority of the callus formation was found in the immediate vicinity of the polymethylmethacrylate without any obvious relationship to trabecular fractures. The results indicate for the first time that, contrary to established knowledge, even in osteoporosis the formation of large amounts of new bone is possible.     

Alveolar bone turnover in male rats: Site- and age-specific changes

Background: This study compares alveolar bone turnover adjacent to distally drifting maxillary first molar teeth of rapidly and slowly growing rats. Methods: Two groups of forty male rats (1 and 3 months) were sacrificed. Sera were analyzed for acid (AcP), alkaline (AlkP), and tartrate-resistant acid phosphatase (TRAP). Bone histomorphometry was done on parasagittal sections of maxillary molars. Molar drift was quantified cephalometrically. Results: Distal surfaces contained more osteoclasts and higher osteoclast percents than mesials at both ages (P<0.001). There were also more osteoclasts on the distals of the older rats as compared to the young (P<0.001). Osteoblast percents were higher (P<0.001) in the older rats on both surfaces. Mesials had higher doublelabeled surface, MAR and BFR than distals in the younger rats (P<0.001). The younger rats had higher (P<0.001) AlkP, AcP, and TRAP. There were no age-specific differences in rat of molar drift. A model of rate of molar drift (P<0.0015) containing bone formation measures accounts for 54.9% of the variability. Conclusions: We conclude that the bone turnover dynamics adjacent to maxillary first molars represent predominantly remodeling on the distal in both groups and modeling on the mesial only in the young rats, that distal molar tooth drift reflects alveolar bone turnover, and that alveolar bone manifests the marked reduction in bone cell activity that occurs in the rat skeleton after 8 weeks but that this reduction is compensated by recruiment or maintenance of more bone cells at these sites. © 1995 Wiley-Liss, Inc.     

促骨形成药物的研究进展

骨质疏松症所引起的脆性骨折严重影响老年人的健康和生活质量。目前,抗骨质疏松治疗的药物主要有骨吸收抑制剂和骨形成促进剂两大类;而临床用于治疗的大多为骨吸收抑制药物,仅有重组人甲状旁腺激素是唯一上市的治疗骨折疏松的促骨形成药物。胰岛素样生长因子-1、钙离子受体拮抗剂、骨形成蛋白、Wnt信号通路阻滞剂等一批新型促骨形成药物正在体内和体外实验之中。随着研究的不断深入,这些促骨形成药物必将会有广阔的应用前景。     

Multiple increased osteoclast functions in individuals with neurofibromatosis type 1

Skeletal abnormalities including scoliosis, tibial dysplasia, sphenoid wing dysplasia, and decreased bone mineral density (BMD) are associated with neurofibromatosis type 1 (NF1). We report the cellular phenotype of NF1 human‐derived osteoclasts and compare the in vitro findings with the clinical phenotype. Functional characteristics (e.g., osteoclast formation, migration, adhesion, resorptive capacity) and cellular mechanistic alterations (e.g., F‐actin polymerization, MAPK phosphorylation, RhoGTPase activity) from osteoclasts cultured from peripheral blood of individuals with NF1 (N = 75) were assessed. Osteoclast formation was compared to phenotypic, radiologic, and biochemical data. NF1 osteoprogenitor cells demonstrated increased osteoclast forming capacity. Human NF1‐derived osteoclasts demonstrated increased migration, adhesion, and in vitro bone resorption. These activities coincided with increased actin belt formation and hyperactivity in MAPK and RhoGTPase pathways. Although osteoclast formation was increased, no direct correlation of osteoclast formation with BMD, markers of bone resorption, or the clinical skeletal phenotype was observed suggesting that osteoclast formation in vitro cannot directly predict NF1 skeletal phenotypes. While NF1 haploinsufficiency produces a generalized osteoclast gain‐in‐function and may contribute to increased bone resorption, reduced BMD, and focal skeletal defects associated with NF1, additional and perhaps local modifiers are likely required for the development of skeletal abnormalities in NF1. © 2011 Wiley‐Liss, Inc.     

关节软骨下骨血管新生的研究进展

骨关节病是一种很常见的疾病,其导致的疼痛及功能障碍对人体健康及生活质量有很大影响,但其发病原因及病理机制尚未完全清楚。近年来,骨关节病患者的软骨下骨改变及血管新生备受重视。本文就骨关节病与软骨下骨血管新生的关系及其研究进展作一综述。     

糖尿病与骨细胞代谢

糖尿病是由于胰岛素分泌异常引起的以慢性长期高血糖为特征的一种代谢性疾病。糖尿病性骨质疏松是骨量减少、骨组织显微结构改变、骨强度减低、骨脆性增加等易发生骨折的代谢性骨病,是糖尿病在骨骼系统的重要并发症。糖尿病性骨质疏松发病机制研究已成为国内外研究热点。     

长链非编码RNAs调控骨稳态研究进展

骨形成和骨吸收是骨稳态维持的两个重要过程,骨稳态失衡可导致多种骨代谢疾病的发生。长链非编码RNAs(lncRNAs)是一类几乎不具有编码功能的RNAs,在调节基因表达、生命发育及疾病发生发展中起重要调控作用。在骨代谢疾病中多种lncRNAs表达异常,lncRNAs通过调节成软骨分化、成骨分化和骨基质矿化过程,调控骨的形成。并通过影响破骨细胞的分化和成熟,参与骨吸收过程的调节。     

Blockade of the OGF-OGFr pathway in diabetic bone

ABSTRACT

Purpose: This research investigated the presence and integrity of the opioid growth factor (OGF)—opioid growth factor receptor (OGFr) regulatory pathway in type 1 diabetic (T1D) rats, and investigated whether modulation of this axis by naltrexone (NTX) altered the composition of normal bone or fractured femurs.

Materials and Methods: Diabetes was induced by streptozotocin; controls rats received buffer. Hyperglycemic animals were subjected to femur osteotomy, with randomized cohorts receiving either topical NTX or sterile saline in calcium carbonate. In experiment 2, hyperglycemic rats were injected daily for 3 weeks with either 30 mg/kg NTX or sterile saline. Expression levels of OGF and OGFr were measured by immunohistochemistry, bone composition was assessed by histomorphometry, and bone integrity was evaluated by µCT and 3-point bending.

Results: Relative to normoglycemic bones, OGF and OGFr expression levels were increased 95% and 84%, respectively, in T1D bone; serum levels of OGF in T1D rats were elevated 23%. Hyperglycemia decreased the strength (26%), osteocalcin expression (17%), and number of proliferative (Ki67+) cells (32%) in intact femur. Topical NTX treatment of fractured femurs reduced the percentage of granulation tissue and increased cartilage. Systemic NTX treatment of diabetic rats increased strength by 21% and energy absorbed by105% in bone relative to measurements in saline-treated diabetic rats.

Conclusions: The OGF-OGFr pathway appears to be dysregulated in the bone of T1D rats. Topical NTX treatment of T1D fractured bone accelerated some aspects of delayed diabetic fracture repair, and systemic NTX protected against some elements of compromised bone composition.     

女性2型糖尿病患者的骨密度变化

目的：探讨女性2型糖尿病与骨质疏松的关系。方法：应用双能X线骨密度仪（DEXA）对56例女性2型糖尿病患者及52例女性健康对照者进行骨密度（BMD）测定,并测定糖尿病患者的空腹胰岛素及餐后2h胰岛素（2h Ins）水平,结合病程、年龄等相关因素进行分析。结果：52例健康对照组中低骨量8例,骨质疏松5例,骨密度减低的发生率为25%;56例2型糖尿病患者中,低骨量16例,骨质疏松23例,骨密度减低的发生率为69.7%,明显高于对照组,差异有显著性（P〈0.01,χ^2=21.524）,骨密度减低者胰岛素水平相对更低。结论：女性2型糖尿病患者的骨质疏松发生率高,且与年龄、病程、胰岛素水平相关。     

雌激素干预骨质疏松大鼠牙槽骨改建过程中白细胞介素1的表达

背景：目前大鼠是骨质疏松研究中使用最多的模型动物,其中大鼠去卵巢动物模型应用最广泛,雌性大鼠在卵巢切除后,其骨质变化和给予雌激素后的反应与人相似。 目的：建立骨质疏松拔牙创愈合的大鼠动物模型,研究雌激素应用对骨质疏松大鼠牙槽骨中白细胞介素1分布及表达的影响。 方法：选用65只纯种3月龄雌性大鼠,按随机数字表法分为2组,骨质疏松模型组40只大鼠在全麻下摘除双侧卵巢,25只假手术组摘除卵巢周围与之大小相同的脂肪组织,常规饲养8周以建立大鼠骨质疏松模型。造模成功后全麻拔除大鼠左侧上颌磨牙,病理彩色图像分析仪分析颌骨变化。在骨质疏松模型组中随机抽取15只皮下注射苯甲酸雌二醇作为雌激素治疗组。免疫组织化学法观察白细胞介素1在各组大鼠拔牙后牙槽骨改建过程中的表达变化。 结果与结论：卵巢切除后,骨质疏松模型组大鼠的骨小梁薄而少,骨小梁间距变宽,颌骨骨强度下降。应用雌激素治疗后,发现雌激素治疗组白细胞介素1的阳性表达较骨质疏松组减少。提示3月龄SD雌性大鼠去卵巢8周后可发生骨质疏松,雌激素治疗对骨质疏松大鼠拔牙创骨愈合牙槽骨中白细胞介素1表达有明显的抑制作用。     

Hypoxia-induced factor-1 alpha upregulates vascular endothelial growth factor C to promote lymphangiogenesis and angiogenesis in breast cancer patients

Hypoxia-induced factor-1 alpha （HIF-1α） affects many effector molecules and regulates tumor lymphangio- genesis and angiogenesis during hypoxia. The aim of this study was to investigate the role of HIF-1α in the regu- lation of vascular endothelial growth factor C （VEGF-C） expression and its effect on lymphangiogenesis and an- giogenesis in breast cancer. Lymphatic vessel density （LVD）, microvessel density （MVD） and the expressions of HIF-1α and VEGF-C proteins were evaluated by immunohistochemistry in 75 breast cancer samples. There was a significant correlation between HIF-1α and VEGF-C （P = 0.014, r = 0.273, Spearman＇s coefficient of correlation）. HIF-1α and VEGF-C overexpression was significantly correlated with higher LVD （P = 0.003 and P = 0.017, re- spectively）, regional lymph nodal involvement （P = 0.002 and P = 0.004, respectively） and advanced tumor, node, metastasis （TNM） classification （P = 0.001 and P = 0.01, respectively）. Higher MVD was observed in the group expressing higher levels of HIF-1α and VEGF-C （P = 0.033 and P = 0.037, respectively）. Univariate analysis showed shorter survival time in patients expressing higher levels of HIF-1α and VEGF-C. HIF-1α was also found to be an independent prognostic factor of overall survival in multivariate analysis. The results suggest that HIF-1α may affect VEGF-C expression, thus acting as a crucial regulator of lymphangiogenesis and angiogenesis in breast cancer. This study highlights promising potential of HIF- 1α as a therapeutic target against tumor lymph node me- tastasis.     

Ontogeny of the human maxilla: a study of intra‐population variability combining surface bone histology and geometric morphometrics

Bone modeling is the process by which bone grows in size and models its shape via the cellular activities of the osteoblasts and osteoclasts that respectively form and remove bone. The patterns of expression of these two activities, visible on bone surfaces, are poorly understood during facial ontogeny in Homo sapiens; this is due mainly to small sample sizes and a lack of quantitative data. Furthermore, how microscopic activities are related to the development of morphological features, like the uniquely human‐canine fossa, has been rarely explored. We developed novel techniques for quantifying and visualizing variability in bone modeling patterns and applied these methods to the human maxilla to better understand its development at the micro‐ and macroscopic levels. We used a cross‐sectional ontogenetic series of 47 skulls of known calendar age, ranging from birth to 12 years, from a population of European ancestry. Surface histology was employed to record and quantify formation and resorption on the maxilla, and digital maps representing each individual's bone modeling patterns were created. Semilandmark geometric morphometric (GM) methods and multivariate statistics were used to analyze facial growth. Our results demonstrate that surface histology and GM methods give complementary results, and can be used as an integrative approach in ontogenetic studies. The bone modeling patterns specific to our sample are expressed early in ontogeny, and fairly constant through time. Bone resorption varies in the size of its fields, but not in location. Consequently, absence of bone resorption in extinct species with small sample sizes should be interpreted with caution. At the macroscopic level, maxillary growth is predominant in the top half of the bone where bone formation is mostly present. Our results suggest that maxillary growth in humans is highly constrained from early stages in ontogeny, and morphological changes are likely driven by changes in osteoblastic and osteoclastic rates of expression rather than differences in the bone modeling patterns (i.e. changes in location of formation and resorption). Finally, the results of the micro‐ and macroscopic analyses suggest that the development of the canine fossa results from a combination of bone resorption and bone growth in the surrounding region.     

CD28 CD8 T cells are significantly reduced and correlate with disease duration in juveniles with type 1 diabetes

Type 1 diabetes (T1D) is a chronic disease caused by autoimmune destruction of insulin-producing pancreatic β-cells. T1D is typically diagnosed in children, but information regarding immune cell subsets in juveniles with T1D is scarce. Therefore, we studied various lymphocytic populations found in the peripheral blood of juveniles with T1D compared to age-matched controls (ages 2–17). One population of interest is the CD28⁻ CD8⁺ T cell subset, which are late-differentiated cells also described as suppressors. These cells are altered in a number of disease states and have been shown to be reduced in adults with T1D. We found that the proportion of CD28⁻ cells within the CD8⁺ T cell population is significantly reduced in juvenile type 1 diabetics. Furthermore, this reduction is not correlated with age in T1D juveniles, although a significant negative correlation between proportion CD28⁻ CD8⁺ T cells and age was observed in the healthy controls. Finally, correlation analysis revealed a significant and negative correlation between the proportion of CD28⁻ CD8⁺ T cells and T1D disease duration. These findings show that the CD28⁻ CD8⁺ T cell population is perturbed following onset of disease and may prove to be a valuable marker for monitoring the progression of T1D.     

Subchondral trabecular structural changes in the proximal tibia in an ovine model of increased bone turnover

Ovariectomized (OVX) sheep are now considered to be useful models for a variety of metabolic bone disorders. The specific aim of this study was to determine the effects of ovariectomy on the structural parameters and material density of the subchondral bone of the ovine tibial plateau as measured by microcomputed tomography (MicroCT). Twenty-three sheep were examined in this study; 10 of the sheep underwent ovariectomy (OVX), and the remainder (n=13) were kept as controls (CON). These animals were then sacrificed at 12 months post-operatively. Three-dimensional analyses were performed of osteochondral samples (15 mm deep) which were obtained from the medial tibial plateau using MicroCT. Bone volume fraction of the subchondral trabecular bone was reduced in the ovariectomized sheep as compared to control animals (0.439 vs. 0.483, P=0.038). Trabeculae were also significantly thinner in the OVX group (0.220 vs. 0.252 mm, P=0.010), with reduced connectivity density (7.947 vs. 11.524 mm(-3) , P=0.014). There was a trend towards lower numbers of individual trabeculae present in the OVX group as compared to controls, but this did not reach significance (2.817 vs. 3.288 mm(-1) , P=0.1). There was also increased trabecular separation in the OVX group, which again fell short of significance (0.426 vs. 0.387 mm, P=0.251). There was no difference in hydroxyapatite concentration (HA) between the two groups (929 vs. 932 mgHA cm(-3) , P=0.687). In conclusion, significant alterations of the trabecular architecture under the tibial plateau were observed following 12 months of oestrogen-deficiency in this ovine model. Despite these marked morphological and structural density differences, the material densities were equal in the two groups.     

Ursolic acid derivative ameliorates streptozotocin-induced diabestic bone deleterious effects in mice

Objective: This study was performed to investigate bone deteriorations of diabetic mice in response to the treatment of ursolic acid derivative (UAD). Methods: The biomarkers in serum and urine were measured, tibias were taken for the measurement on gene and protein expression and histomorphology analysis, and femurs were taken for the measurement on bone Ca and three-dimensional architecture of trabecular bone. Results: UAD showed a greater increase in bone Ca, BMD and significantly increased FGF-23 and OCN, reduced PTH and CTX in diabetic mice. UAD reversed STZ-induced trabecular deleterious effects and stimulated bone remodeling. The treatment of STZ group with UAD significantly elevated the ratio of OPG/RANKL. Moreover, insulin and IGF-1 showed a negative correlation with both FBG and Hb1Ac in STZ group. We attributed down-regulating the level of Hb1Ac in diabetic mice to that ursolic acid derivative could primely control blood sugar levels. After analyzing of two adipocyte markers, PPARγ and aP2, increased expression in the tibias of diabetic mice, and UAD could improve STZ-induced adipocyte dysfunction. Conclusions: These results demonstrated that UAD could ameliorate STZ-induced bone deterioration through improving adipocyte dysfunction and enhancing new bone formation and inhibiting absorptive function of osteoclast in the bone of diabetic mice.     

Low dose streptozotocin-induced diabetes in mice: reduced IL-2 production and modulation of streptozotocin-induced hyperglycemia by IL-2.

The possible role of interleukin 2(IL-2) in the pathogenesis of multiple low dose streptozotocin (Sz)-induced diabetes in mice was analysed. Spleen cells from diabetic male C57Bl/6 mice showed diminished mitogen-induced IL-2 production as determined by bioassay using the IL-2-dependent T-cell line CTLL-2. In parallel the proliferative response was reduced. Systemic daily administration of human recombinant IL-2 for 3 weeks had dose-dependent effects on the development of hyperglycemia in Sz-treated (5 x 40 mg) mice: while IL-2 at doses of 1 x 2, 1 x 10, 2 x 10 micrograms/kg body weight caused partial suppression of hyperglycemia, higher doses (2 x 20, 2 x 40 micrograms/kg) had an enhancing effect. Treatment with the lowest dose (1 x 1 micrograms/kg) or with a control preparation from bacteria (2 x 10 micrograms/kg) did not significantly alter the course of diabetes. Effects of IL-2 were similar when treatment was started concomitantly with or only after streptozotocin injections. This observation argues against the direct interaction between IL-2 and streptozotocin but suggests modulation of immune reactivity by IL-2. Our findings of decreased mitogen-stimulated IL-2 production by splenic lymphocytes, and the disease-modulating effect of IL-2 in the low-dose streptozotocin diabetes extend our previous observations in spontaneously diabetic BB rats and further support the notion of an involvement of IL-2 in the control of autoimmune diseases.